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Livermore
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Penumbra Inc

PEN
Exchange
NYSE
Industry
Surgical & Medical Instruments & Apparatus
SEC CIK
0001321732

No open-market purchases or sales by Penumbra Inc insiders were filed in the last 90 days; 452 institutions reported holding it in 13F filings for Q2 2026, worth $10.8B in total; no superinvestor holds it.

Four kinds of short-selling data, each measuring something different:

  • Short interest: shares sold short and not yet bought back, as of a settlement date. FINRA publishes it twice a month, about eight business days after the settlement date.
  • Daily short volume: shares sold short each day in off-exchange trades reported to FINRA. It counts trades, not open positions, and is published the next day.
  • Fails-to-deliver: shares not delivered by the settlement date. The SEC publishes them twice a month, about two weeks late.
  • ATS (dark pool) volume: weekly volume on alternative trading systems and other off-exchange venues. FINRA publishes it two to four weeks after the week.

More in the glossary.

Short interest

Shares sold short and not yet bought back, from FINRA, on every settlement date in the last two years.

Short interest
2.40M
Shares, settlement Oct 30, 2026
Change
+140.6K
+6.2% vs. Oct 15, 2026
Days to cover
5.29
Short interest ÷ average daily volume
Average daily volume
454.0K
Shares, as reported by FINRA
Short interest by settlement date
Oct 31, 2024: 2,255,992 sharesNov 15, 2024: 1,923,333 sharesNov 29, 2024: 1,850,438 sharesDec 13, 2024: 1,783,912 sharesDec 31, 2024: 1,836,735 sharesJan 15, 2025: 1,872,148 sharesJan 31, 2025: 1,434,305 sharesFeb 14, 2025: 1,678,058 sharesFeb 28, 2025: 1,355,515 sharesMar 14, 2025: 1,224,870 sharesMar 31, 2025: 1,485,054 sharesApr 15, 2025: 1,570,778 sharesApr 30, 2025: 1,540,416 sharesMay 15, 2025: 1,510,993 sharesMay 30, 2025: 1,293,518 sharesJun 13, 2025: 1,521,978 sharesJun 30, 2025: 1,896,883 sharesJul 15, 2025: 1,830,104 sharesJul 31, 2025: 1,515,865 sharesAug 15, 2025: 1,631,808 sharesAug 29, 2025: 1,789,005 sharesSep 15, 2025: 1,978,313 sharesSep 30, 2025: 1,612,966 sharesOct 15, 2025: 1,733,518 sharesOct 31, 2025: 1,819,291 sharesNov 14, 2025: 1,687,371 sharesNov 28, 2025: 1,514,769 sharesDec 15, 2025: 1,607,603 sharesDec 31, 2025: 1,709,674 sharesJan 15, 2026: 1,722,051 sharesJan 30, 2026: 1,601,731 sharesFeb 13, 2026: 1,863,136 sharesFeb 27, 2026: 1,866,429 sharesMar 13, 2026: 2,061,336 sharesMar 31, 2026: 2,437,639 sharesApr 15, 2026: 2,007,168 sharesApr 30, 2026: 1,896,966 sharesMay 15, 2026: 1,916,276 sharesMay 29, 2026: 1,916,131 sharesJun 15, 2026: 1,986,919 sharesJun 30, 2026: 2,037,620 sharesJul 15, 2026: 2,123,757 sharesJul 31, 2026: 1,836,046 sharesAug 14, 2026: 1,818,794 sharesAug 31, 2026: 1,731,493 sharesSep 15, 2026: 1,805,942 sharesSep 30, 2026: 2,245,649 sharesOct 15, 2026: 2,262,502 sharesOct 30, 2026: 2,403,093 shares
Short interest in PEN by settlement date
Settlement dateShort interestChangeChange %Avg. daily volumeDays to cover
Oct 30, 20262.40M+140.6K+6.2%454.0K5.29
Oct 15, 20262.26M+16.9K+0.8%334.5K6.76
Sep 30, 20262.25M+439.7K+24.4%472.6K4.75
Sep 15, 20261.81M+74.4K+4.3%251.7K7.18
Aug 31, 20261.73M−87.3K−4.8%287.6K6.02
Aug 14, 20261.82M−17.3K−0.9%260.3K6.99
Jul 31, 20261.84M−287.7K−13.6%438.2K4.19
Jul 15, 20262.12M+86.1K+4.2%337.2K6.30
Jun 30, 20262.04M+50.7K+2.6%399.6K5.10
Jun 15, 20261.99M+70.8K+3.7%431.1K4.61
May 29, 20261.92M−1450.0%460.9K4.16
May 15, 20261.92M+19.3K+1.0%411.9K4.65
Apr 30, 20261.90M−110.2K−5.5%578.7K3.28
Apr 15, 20262.01M−430.5K−17.7%473.3K4.24
Mar 31, 20262.44M+376.3K+18.3%655.4K3.72
Mar 13, 20262.06M+194.9K+10.4%662.1K3.11
Feb 27, 20261.87M+3.29K+0.2%622.7K3.00
Feb 13, 20261.86M+261.4K+16.3%973.7K1.91
Jan 30, 20261.60M−120.3K−7.0%1.77M1.00
Jan 15, 20261.72M+12.4K+0.7%1.61M1.07
Dec 31, 20251.71M+102.1K+6.4%395.8K4.32
Dec 15, 20251.61M+92.8K+6.1%509.3K3.16
Nov 28, 20251.51M−172.6K−10.2%495.9K3.05
Nov 14, 20251.69M−131.9K−7.3%572.6K2.95
Oct 31, 20251.82M+85.8K+5.0%394.7K4.61
Oct 15, 20251.73M+120.6K+7.5%325.5K5.32
Sep 30, 20251.61M−365.3K−18.5%418.5K3.85
Sep 15, 20251.98M+189.3K+10.6%481.8K4.11
Aug 29, 20251.79M+157.2K+9.6%466.1K3.84
Aug 15, 20251.63M+115.9K+7.7%401.0K4.07
Jul 31, 20251.52M−314.2K−17.2%594.9K2.55
Jul 15, 20251.83M−66.8K−3.5%394.7K4.64
Jun 30, 20251.90M+374.9K+24.6%465.5K4.08
Jun 13, 20251.52M+228.5K+17.7%443.6K3.43
May 30, 20251.29M−217.5K−14.4%447.5K2.89
May 15, 20251.51M−29.4K−1.9%662.5K2.28
Apr 30, 20251.54M−30.4K−1.9%659.3K2.34
Apr 15, 20251.57M+85.7K+5.8%468.3K3.35
Mar 31, 20251.49M+260.2K+21.2%425.4K3.49
Mar 14, 20251.22M−130.6K−9.6%413.7K2.96
Feb 28, 20251.36M−322.5K−19.2%672.2K2.02
Feb 14, 20251.68M+243.8K+17.0%453.2K3.70
Jan 31, 20251.43M−437.8K−23.4%442.2K3.24
Jan 15, 20251.87M+35.4K+1.9%533.2K3.51
Dec 31, 20241.84M+52.8K+3.0%334.9K5.48
Dec 13, 20241.78M−66.5K−3.6%287.7K6.20
Nov 29, 20241.85M−72.9K−3.8%295.2K6.27
Nov 15, 20241.92M−332.7K−14.8%367.4K5.23
Oct 31, 20242.26M−398.2K−15.0%405.2K5.57

Fails-to-deliver

Shares that weren't delivered by the settlement date, from the SEC, for the last 30 dates with fails. The price is the previous day's closing price published by the SEC.

Fails-to-deliver in PEN by settlement date
Settlement dateSharesPriceValue
Oct 14, 2026966$320.01$309.1K
Oct 13, 2026127$320.96$40.8K
Oct 9, 20262$317.52$635.04
Oct 8, 202616,654$316.35$5.27M
Oct 7, 20264,861$317.05$1.54M
Oct 2, 2026203$318.00$64.6K
Oct 1, 202625$318.34$7.96K
Sep 30, 20261$318.86$318.86
Sep 29, 20262$319.18$638.36
Sep 28, 20264$318.89$1.28K
Sep 25, 20269$319.72$2.88K
Sep 24, 2026557$319.44$177.9K
Sep 23, 202623$319.39$7.35K
Sep 10, 20261$319.57$319.57
Sep 4, 2026301$321.14$96.7K
Sep 2, 20262,134$322.58$688.4K
Aug 28, 20261,261$321.00$404.8K
Aug 24, 202617$325.18$5.53K
Aug 21, 20261,378$323.76$446.1K
Aug 20, 202617$326.84$5.56K
Aug 19, 20264$324.75$1.30K
Aug 18, 202620$327.17$6.54K
Aug 17, 202640$327.02$13.1K
Aug 13, 20269$326.58$2.94K
Aug 12, 202616,343$326.28$5.33M
Aug 11, 20261,602$325.98$522.2K
Aug 10, 2026176$324.66$57.1K
Aug 6, 20269$323.21$2.91K
Aug 5, 2026307$324.22$99.5K
Aug 3, 2026478$321.19$153.5K

Daily short volume

Off-exchange short-sale volume, not short interest: shares sold short each day in trades reported to FINRA, for the last 30 trading days.

The short volume ratio isn't a sentiment gauge: market makers sell short to fill buy orders and to hedge, so short sales are usually about half of off-exchange volume.

Off-exchange short volume in PEN by trade date
Trade dateShort volumeShort exemptOff-exchange volumeShort volume ratio
Nov 10, 202616,296054,80729.7%
Nov 9, 202640,0361477,90951.4%
Nov 6, 202646,973465,56571.6%
Nov 5, 202656,3766078,74871.6%
Nov 4, 202638,3984182,47646.6%
Nov 3, 202648,141800109,46644.0%
Nov 2, 202659,1080124,16147.6%
Oct 30, 202671,52683141,11050.7%
Oct 29, 2026105,3676189,83555.5%
Oct 28, 2026150,1560329,20745.6%
Oct 27, 202637,0060122,75430.1%
Oct 26, 202657,89010163,53135.4%
Oct 23, 202671,9630134,84053.4%
Oct 22, 202636,3644155,46623.4%
Oct 21, 202667,1880122,99754.6%
Oct 20, 202669,577367139,85849.7%
Oct 19, 202639,367566,04759.6%
Oct 16, 202657,4552899,65357.7%
Oct 15, 202660,104197,56261.6%
Oct 14, 202659,45825102,47758.0%
Oct 13, 202640,6272066,77660.8%
Oct 12, 202657,8790119,86048.3%
Oct 9, 2026100,6880225,49044.7%
Oct 8, 202685,7840128,49066.8%
Oct 7, 202686,6341113,08776.6%
Oct 6, 202666,1091129,06451.2%
Oct 5, 202652,301199,82552.4%
Oct 2, 202653,8640106,25950.7%
Oct 1, 2026100,6000164,95061.0%
Sep 30, 202670,6740141,47150.0%

ATS (dark pool) volume

Weekly volume on alternative trading systems (ATS) and other off-exchange (OTC) venues, from FINRA, for the last 12 weeks. ATS share is ATS volume ÷ (ATS + OTC volume), not a share of all trading.

Weekly ATS and OTC volume in PEN
Week ofTierATS sharesATS tradesOther OTC sharesOther OTC tradesATS share
Oct 19, 2026T1515,47815,024137,1374,23779.0%
Oct 12, 2026T1406,93215,15486,8624,10282.4%
Oct 5, 2026T1478,52917,809229,2727,77067.6%
Sep 28, 2026T1427,64518,135194,7806,50668.7%
Sep 21, 2026T1837,34627,302239,8336,19577.7%
Sep 14, 2026T1691,25023,411658,3084,78551.2%
Sep 7, 2026T1256,99613,355149,4724,15263.2%
Aug 31, 2026T1215,40614,243283,7402,93343.2%
Aug 24, 2026T1458,63819,401170,9793,23472.8%
Aug 17, 2026T1309,08216,23973,0262,95380.9%
Aug 10, 2026T1249,67812,641193,9353,03656.3%
Aug 3, 2026T1446,25423,167138,2604,46676.3%